Indexing apparatus for marking devices and the like



Aug. 20, 1963 1, s. AYERS ETAL 3,101,013

INDRXING APPARATUS RoR MARKING DEVICES AND TRE LIRE Filed Oct. 26, 19593 Sheets-Sl'lee'tl 1 INVENToRs John S. Ayers 8 Alvin M.Brown BY I M,Mami 'DI t ATTORNEYS Aug. 20, 1 963 Y J. s. AYERs ETAI. 3,101,013

` INDEXNGV APPARATUS FOR MARKING DEVICES AND THE LIKE Filed Oct. 26,1959 3 Sheets-Sheet 2 INVENTORS John S. Ayers 8 By Alvin M. BrownATTORNEYS Aug. 20, 1963 J. s. AYERs ETAL 3,101,013

INDEXING APPARATUS FOR MARKING DEvIcEs AND THE LIKE 5 Sheets-Sheet 3Filed OCT.. 26, 1959 JON mvENToRs: John S. Ayers Alvin Brown M y MMATTORNEYS:

United States Patent O 3,1l1,lll3 INDEXING APPARATUS FOR MARKING DEVICESAND THE LIKE John S. Ayers, Scott Township, Allegheny County, and AlvinM. Brown, Penn Township, Allegheny County, Pa., assiguors to las. H.Matthews & Co., Pittsburgh, Pa., a corporation of Pennsylvania FiledOct. 26, 1959, Ser. No. 848,740

5 Claims. (Cl. 74-S18) This invention istor an indexing apparatus forselectively adjust-ing ia movable element to a predetermined settingfrom a remote location. The invention, while being applicable to variousoperations, is particularly useful for operating relatively heavymovable parts whose position must be accurately adjusted. The inventionis especially useful for rotating marking dies for marking steel billetsand slabs with data that is usually marked on such products to identifythe billet or slab as to theheat number, date and perhaps codedinformation as to its composition, or like markings.

IIn billet marking machines disclosed in certain prior applications inwhich -We are co-inventors; namely, Serial No. 737,041 tiled May 22,1958, now Patent No. 3,0201,- 834, granted IFebruary 13, 19612, SerialNo. 765,513, tiled October y6, 1958, now Patent No. 3,002,918, there isdisclosed a marking device having a marking head comprised of iaplurality of gear wheels in side-by-side relation, each beingindependently rotatable and each having an impression forming markingcharacter -on the outer ends of the gear teeth thereof. Mechanism isprovided for advancing the marking head into contact with the edge ofthe slab or billet and when Contact has been made, the marking head isstruck ia heavy blow, whereupon the characters on those gear teeth ofthe marking head which contact the billet make an impression in thebillet. The marking head is then retracted and in the retracted positioneach gear die is engaged by a separate indexing gear. The `selectiverotation of the indexing gears may then be effected to rotate the geardies tov bring diierent characters into marking position. The indexinggears are -rotated in step-by-step increments through pawls which arereciprocated by pneumatic cylinders, each reciprocation of a pawlrotating the indexing gear one tooth, and such rotation is in turntransmitted to the gear die.

It is necessary that the indexing be effected from a consol or panelremote from the marking head and that it be rapidly but accuratelyeffected. The gear dies must be heavy to withstand the impact, and theentire system must be fool-proof and secure against error due tojarring, failure of ia pawl to effectively ratchet, or error due to somebounce or inertia ecect that occurs when heavy parts such as are here4involved are moved rapidly or stopped or their direction of movementsuddenly reversed.

In a copending yapplication Serial No. 765,513 tiled October 6, 1958 inwhich we are co-applicants, the indexing is effected through electriccircuits responsive to the reciprocation of the pawl thatrotates theindexing gears and which include stepping relays that are energizedthrough such limit switches. While this system is normally satisfactory,it is subject to possible error since it really counts thereciprocations of an operating pawl and not the actual rotation of theindexing gear. Bouncing or jarring or inertia may result in a movementof `a pawl with no corresponding movement or improper movement of auindexing Wheel. Should this happen, the stepping relay would reach theintended setting ahead of `or out of phase with the actual turning ofthe gear die to the selected character, so that `an erroneous markingmight be made, and the operator at the consol would be unaware of itbecause he must assume that the indexing mech- 3,101,013 Patented Aug.20, l 963 ICC ' indexing the several dies must be conned in a relatively'indexing gear to properly rotate cannot occur.

small space.

An `object of the present invention is to provide an indexing systemwhich is responsive tothe movement of the indexing gears directly asdistinguished from movement of fthe pawls, whereby any error due tofailure of an Since the indexing gears lare meshed with the markinggears, the marking gears must correspondingly move with each incrementof movement of the indexing gears, and error cannot occur.

A further object of our invention is to provide an indexing mechanismthat will not `be disturbed by the jarring of the machine or possiblebounce lot' any of the parts. i

A further object of our invention is to provide an indexing system whichwill continue to operate until the gear die has moved to its selectedposition and provide an indication at the control panel or consol onlywhen the selected character is in marking position.

A -further important object of our invention is to eliminate steppingrelays from the selector circuit and provide switch means operated bythe movement of the indexing gears to operate the pawls until theselected character is in marking position, simplification of thecircuits being also accomplished by elimination of stepping relays.

These and other objects and advantages are secured by our invention aswill more fully appear from the detailed description thereof inconjunction with the accompanying drawings, in which:

FIG. 1 is a more or yless schematic view of the indexing gears andoperating mechanism thereforV with a portion lof the circuits forcontrolling the same;

FIG.'2 is an elevation on Aa larger scale showing the indexing gear andthe'` contact Wheel operated thereby;

FIG. 3 is a transverse section through one of the con- .tact Wheels inthe plane iof line III-III of FIG. `2; and

FIG. 4 is a schematic simplified circuit diagram for the system; `and iFIG. 5 is a yfragmentary View showing an alternate torni of contactorfor use in the indexing head, the view being partly in verticaltransverse section and partly in elevation.

In the drawings we have shown a single indexing gear and associatedparts and control circuit therefor, `and it is to be understood thatthis is substantially duplicated (except for the rectifier andtransformer) for each marking die or other-member to be indexed.,

Referring iirst to FIG. lof the drawings, we have shown the marking headin dotted lines, -and it is designated generally as 2. Itis shown in:the retracted position land i-t moves toward the right as viewed inFIG. l to engage a face of the billet or slab to be marked. A singlegear idie is indicated at 3 and the end faces of the teeth havecharacter imprinting 'dies thereon, one character on each tooth.Typically these characters may comprise the numerals 0 to 9, or asuccession of letters of the alphabet. The tooth in position 3a of thegear :die 3` is the one which is selected rto mark. The construction andoperation of the marking head and the Courel-ated movement of theindexing head is more fully described in `appl-ication Serial No. 737,041 and brief reference is made thereto only to enable 4the `objectsand purposes of the present invention 'to be more fully understood.

The indexing head I4 in the billet marker `above refer-red tois mounted'on a vertically movable support 4a by which the indexing head is movedinto and fout of engagement with the gear dies of the marking head. The

Vmovement of the indexing gear is transmitted to the gear die 3 torotate'it one increment. 'Fixed in the indexing p head is apivotedholding pawl 11 that holds the indexing gear against free rotation andprevents any over-travel. it is normally held in gear llocking positionby a ieaf spring 1-2 and is tripped by tan abutment 13 fon the slide Asexplained above, and as more ful-ly described in the copendingapplications above last referred to, we have here shownbut one indexinggear and operating rod 6,

Y but the complete machine embodies a head in which there would beseveral of these gears and operating bars in side-by-side relation andthe single shaft 9 would carry all of the indexing gears.

y The rod ty has an lopenating yextension 14 that passes through lacylinder 15, the rod having a piston 16 aixed thereto inside fthecylinder. The cylinder has a port at each end in which is entered .apipe, the pipe at one end being designated 16a and at the other end 1Gb.These pipes lead to a slide valve 17 of va well known type in whichthere is a reciprocating valve element 18. The valve body has exhaustports '19 :and two spaced lair inlet ports leading from Van air supplypipe 2d. The arrangement is such that when the valve '17 admits air frompipe 2()` to one end tot the cylinder 15 the other end of the cylinderis vented to atmosphere. The valve is shown in the drawings in aposition rwhere piston 16 has completed its stroke tothe lett'tand theoperation is about to reverse. This is the normal or rest position ofthe parts. The valve is magnetically operated in yone direction and thenthe other, and this is indicated in the drawings where the ends of theslideV valve project beyond the valve housing and constitute armatures17a and 17b for solenoids 17e` and 17d respectively. These solenoids areenergized through micro-switches 21 tand 22 that are arranged to` beengaged by abutments 21a fand v2lb respectively on the pis-1 ton rod 14so positioned that the micro-switches will be tripped at Vthe oppositelimits of travel of the piston 16.`

'Y The switches 21 and 22 eachhave one poile connected to a currentsupply line 23. The other pole of switch 21 is connected through wire 24with :solenoid 17`c and the other pole of switch 22 is connected throughwire 25 with solenoid 17d. The other terminals of the solenoids are Yconnected to a return conductor indicated by the ground vof the valve 17to be shifted to the right as viewed in this diagram. When this shift ismade, the left-hand port 19' Y will be closed `and air can enter frompipe 2t) and iiow through pipe 16h to the left :end of cylinder 15. Thiswill drive piston 16 to the right, moving the pawl 7 on rod 6 to theright of gear 10. As piston 16 reaches the righthand limit of travel,abutment 2lb engages switch 22 to close it, energizing solenoid 17d toshift the slide valve to the opposite limit of its travel, so that theleft port 19 is vented to atmosphere and yair tlows from pipe 2d intopipe 16a and the opposite end of the cylinder 15 to drive piston 16 tothe left. As the rod 6 moves to the left, pawl 7 rotates the index gearwheel 1d through one increment. As the piston returns again to theleft-hand l limit of traveL-switch 21 is tripped and the cycle isrepeated, and this operation will continue asv ilong as wire 23 remainsenergized. The present invention is'primaniiy concerned with the openingand closing of the circuit to the wire `23 and associated circuits. Amagnetic single pole double throw switcher relay is shown at 26`in HG.l,

and when this switch is in the position in which the switch is thereshown, Vthe Wire 23 is connected with a source of energizing current.The relay has a coil 26a and an armature 26h .and its biased to normallyassume the position shown in FIG. l when the coil 26a is not energized.

According to the present invention, the rotation of the indexing gearwheel 10 in combination with a selector switch at the operators consolcontrols the operation of the switch 26. As here shown, there is iamultiple contact switch 27 in the form of -a second gear wheel supportedon a shaft 28 on theindexing head ywith the teeth of this gear wheelmeshing with the teeth of the gear wheel it?. It might have wide pitchedteeth, like the gear die 3, but is here shown yas having two teethoperating as a single tooth between two teeth of the indexing gear wheel1d. Gear wheel 27, as best shown in FIGS. 2 and 3, is a ber gear orwheelmade of insulating material. On one face is ,a conducting disk or plate29 `of metal. There `is Ia spiral series of contact posts on this platewhich pass through the face of the switch, the ends of which are exposedon the opposite surface of the switch 27. Each pin is arcuately andradially separated from the others and they `are all designated with t.e letter P in FIG. l2.

wiper 32 vfor each'pin P. They are so positioned that they bear vagainstthe :surface of the Agear wheel 27 on a line corresponding to radius Rin FIG. 2, and each wiper is wide enough to contact only one of the pinsP. Thus, as

' the gear wheel 27 is rotated, rst one pin P andl then the -next willin turn =be carried into contact with one of the wipers 32. There is aseparate wire 33 leading from each of these wipers 32 through arnultiple conduct-orecable, designated as 34, to a selector switch 35that may be located in a consol or control panel remote Vtrom themarker. This is usually nearby, but comfortably removed from themachine.

At the selector switch the cable branches out into a number of wires 36corresponding to the number of wires 33 and Wipers'32, and each of thesewires terminates at a switch contact 37. There is an adjustable switcharm 38 manually adjustable to selectively engage any one contact 37, sothat when the switch arm 3S is on a selected contact, a circuit may becompleted from the selected contactto a corresponding '-wiper 32, and'when the gear 10 moves to the right position, the circuit will tbeclosed through the pin P for that wiper to the disk 29 and brush 30.

Referring now toFIG. 4, the manual selector switch 35 is indicated inthe upper left corner of the figure, and the multiple contact switch onthe gear 27 is indicated below it. Itis here ydiagrammatically indicatedfor clarity of illustration as a switch having a numlber lof contacts`arranged in an arc rather than being shown according to its actualconstruction, but each contact 32 corresponds to a contact 32V of FIG.2.

. The selector system with the multiple contact switches is preferablyoperated at low voltage, wherefore current from supply linesd and 41 ispassed through the primary of a stepadown transformer 43. The secondaryof this transformer is .designated 44, and one side of the secondary isconnected to a .Wire 45 leading'to one side of a relay coil 26a ofswitch or relay 26. The other side of the relay coil is connectedthrough wire 46 with manual selector switch Varm 38. The contacts 37 ofthis selector switch lead through wires 36 and cable 34 to Wires 33leading to the several brushes 32. The circuit from wipers 32 is throughone of the pins P and disk 29 (indicated as a swinging switch arm 29 inFIG. 4), brush 30 through wire 46 to the other side of the secondary 44of the transformer 43. Thus it may ybe seen that only when the circuitmay be completed through the selected Contact on the selector switch 35and the corresponding pin P on the gear-actuated multiple contact switch27 will the electromagnet 26a of the control switch or relay 26 beoperated. i

Wire 40 connects to both contacts 26o and 26d of the relay switch 26.Contact 26e of the relay switch connects to Wire 23 leading to the twomicro-switches 21 and 22 as above described, and through one or theother valveoperat-ing solenoids 17d-17e to ground or return current:supply line 41. There is a switch 47 in line 40, diagrammaticallyindicated in FIGS. l and 4 that is closed when the indexing head 4 movesdown into the operating position to closedposition, and which is biasedto open when the indexing head is raised.

When the condition arises that the circuit is closed through the manualselector switch 35 and the gearoperated switch, relay magnet 26a isenergized, lifting the armature of the relay to open the circuit fromcontacts 26e and 26e :of switch 26 and close a circuit across con-`tacts 26d and 261. Current then flows from line 40 through contacts 26dand a signal lamp 49 to ground. A branch circuit 50 leads through relayWinding 51 to ground. The energizing of relay `e1 closes switch 51a.This switch is in series with like switches Ifor each of the otherindexing wheels of the indexing head, for which reason the balance ofthe circuit is indicated in dotted lines. If there are, for example,nine indexing wheels, a switch corresponding to 50`51a for each wheelwould have to close, whereupon a circuit would then be complete througha main indicator lamp 52. Also the circuit would then be establishedthrough this series of switches and line 53 to the stamp-operatingswitch 54, so that when the operator pushed the switch54 down, currentwould flow through this switch to those electro-pneumatic devices thatmove the marking head 2 toward the object to be marked and eitect themarking operation as more fully described in the last two applicationsabove mentioned. The operation may now be completely followed. Theoperator sets selector switch arm 38 to the character which he wantsnext to -be brought into marking position. When the indexing head 4moves down to operating engagement with the marking head 2, switch 47 isclosed, so that current flows through line 40, contacts 26c--26e ofswitch 26 to micro-switch 21, which at that time is closed. Thisinitiates the reciprocation of piston 16 to move the rod 6 and turn theindexing gear 10, and thereby turn marking die 3. Rotation of theindexing wheel 10 also rotates contact gear wheel 27. The reeiprocationof the piston 16 continues automatically upon the closing of switch 47until a circuit is completed through the selected contact of switch 35and the corresponding contact of switch 27 to energize relay Winding 26ato open the circuit between contacts 26C and 26e to stop rfurtherreciprocation of the pawl 7. It will be seen that until switch 47 isclosed by the supp-ort 4a lowering to a position where indexing gear 10meshes with ygear die 3, no :operation of the indexing gear can beeffected. It is therefore possible for the operator to pres-select theposition of the switch arm 38 when the support 4a is raised, with nooperation of the indexing gear taking place. Since the complete machineembodies several marking dies and, therefore, several selector switches35, it is an advantage that the manual selector switches can be adjustedat the operators consol while the marking cycleis being carried out, andthus be set in advance of the return of the marking head to itsretracted position when the support 4a is next lowered.

For the further utility of the device, and to reassure the operator thatthe proper number has been set and enable the operator to makecorrection if he has set his selector dial at the wrong setting, thesystem may include a second switch 60 operating with a gear Wheel 27, as

indicated by the diagram in FIG. 4. This switch has contacts 61corresponding in character sequence to the ones above it in the diagram.Each contact 61 has a wire 62 leading therefrom to a cable 63, theAwires of which lead to the several contacts of a so-called nixie lamp`64, which is a -glow tube having a number of characters therein, aselected one of which will glow when its circuit is energized, suchlamps being well known in the art. The common terminal of the nixie lampis connected to one o utput 65 of rectifier 66 The other output terminalof the rectifier is connected through line 67 with the moving Contact 66of the switch 66. The lamp operates on 200 volts, direct current. Theinput terminals of the rectitier are connected across lines 68 leadingto the output terminals of the voltage step-up transformer `69. Theprimary of this transformer is connected through Wire 70 across thecurrent supply lines 4t? and 41.

The circuit described causes the selected character on the nixie lightto glow when the indexing wheel 10 has moved to the chosen position,which will be at the same time lamp 49 is lighted, giving the operatortwo signals that the particular wheel is at the pre-selected position.It will be apparent to those skilled in the art that while two switchesoperating in unison are shown in the diagram, the etfect of two switchesmay be secured electrically through the use of blocking circuits orrelays separating the alternating and direct current circuits, and thatthe simplified wiring digram of FIG. 4 is more or less symbolic orschematic.

In the particular system shown, the marking Wheel or gear dies isseparate from the indexing gear Wheel, but in sorne instances, as forexample with rubber stamps used for making boxes, the indexing wheelmight itself be a type of marking wheel, or the Wheel switch 27 might bea marking wheel, or one wheel could combine all of the functions of thethree wheels here shown.

However, the system here shown is especially adapted for a billet orslab marker where the gear dies are heavy, the setting of the dies fast,and bouncing or jarring is likely to occur. lf the pawl 7 fails to catchon the indexing gear, the mechanism must continue to operate until itdoes, or ior such length of time that the operator knows that there is afailure of the indexing wheel to turn, and shut the machine down forrepair or adjustment. Since all operations of the contact gear `27, themarking wheel 2 and the indexing wheel 10 occur when the gears are inmesh, movement of any gear will reliect correspondingly on the others.

In FIG. 5 we have shown an alternative form of contactor on the indexinghead. In this View, the gear 27 corresponding to -gear 27 in FIG. 2 ismade of conducting material, andinstead of having a succession ofcontact pins P as in FIG. 2, it carries a single brush, 27a. Alongsidethe gear 27 there is a lixed arm or plate 31 in the location of part 31of FIG. 2, but in this case it has a circular series of equally spacedcontacts 32 thereon arranged to be engaged in succession by the brush27a as the gear 27 rotates. A wire 33' corresponding to wires 33"f FIG.2 leads from each contact 32' while a brush 30 connected to wire 46 isthe counterpart of brush 30 in FIG. 2, in that a circuit may becompleted through brush 3G to ,gear 27 to brush `27a and from this brushthrough a contact 32 on fixed support 31 to Wire 33'. Except -for therotating multiple contact switch construction, the circuits for FIG. 5would be the same as above described.

It will be understood that while we have shown one embodiment of ourinvention, various changes and modiiications may be made in theconstruction and arrangement of partsrwithin the contemplation of ourlinvention.

We claim:

l. An indexing apparatus comprising an indexing gear, a pawl `mechanismmovable between two positions engaging the indexing gear in onedirection of movement only to rotate the gear incrementally, a uid motorincluding a reciprocating piston and a rod, the red extending beyond themeter and connected to the pawl mechanism for imparting rectilinearmotionk thereto, a fluid slide valve having a reciprocating slideelement therein, armatures connected to the slide element for movementtherewith and extending beyond the valve at opposite ends of the slideelement,pconduits how-connecting the fluid slide valve with the motorfor introducing fluid from the Valve to operate the motor pistonselectively from one pesitionto another whereby the motor piston rod isreciprocatecl, solenoid coils connected in parallel and coupledmagnetically te each of the armatures, a source of current connected toeach of the solenoid coils, a switch connected in series lwith each ofthe solenoid coils and the source of current, beth switches beingnormally open and positioned for tripping alternately by travel of thepawl mechanism such that the coils are energized alternately to move theslide element'of the valve `for controlled movement of the motor pistonby dluid ported from the valve selectively onrboth sides of the piston,a relay with a contacter connected in series between the current sourceand the switches and with a coil for operating the coni taeter to closethe circuit from the source to the switches in Vone kposition and teopen the circuit in another position, a manually adjustable switch with`a plurality of contacts and a contacter selectively movable to any oneof the contacts, :a rotary switch with a contacter operatively connectedte the indexing gear for rotation and includingT a plurality of contactscorresponding to the contacts ofthe selector switch, the correspondingcontacts Vof the rotary switch and the selector switch beingAelectrically connected, the electrical source being connected seriallyto both the contacter of the selector switch and the'centactor of therotary switch whereby a closed circuit is 4formed joining the source tothe selector switch contacter and eneof its contacts to a correspondingcentact of the rotary switch and its contacter back to the source, andthe relay coil being in series connection with the source and theselector switch contacter wherebythe coil is energized whencorresponding contacts of the selector switch and the rotary switch arecontacted by the `contactors of such switches te move the relaycontacter te the other position to open the circuit from the source tothe switches connected to the solenoid coils for stepping the action ofthe valve and motor and the rotation of the indexing gear. l

2. An indexing apparatus as defined in claim 1 includ- Vinga1 suppentmovable from a iirst position to a vsecondV position; the rndexinggearbeing mounted for rotation on S switch being open when the support ismoved to the irst position whereat the indexing gear and the gear dieare disengaged.

3. An indexing apparatus as in claim 1 wherein the s rotary switchcontacts are pins in radially spaced arrangement on a wheel and a seriesof brushes are lixed in the path oftravel of thepins with one brushpositioned for wiping contact with each pin, each of the brushes beingelectrically connected to a contact `of the selector switch,

and the source of current being connectedto each et the dicating circuitincluding an indicating device is cennected to the relaygcontactor whenit is moved vrte the other position, the contacter electricallyconnecting the indicating circuit with the source of current when therelay is in such other position which is effected when the relay coil isenergized by completion of a circuit from the source through a selectorcontact and corresponding contact of the rotary switch.

5. An indexing Vapparatus as in claim 1 wher-ein a further rotary switchis provided with a contacter mechanically connected to the 'rotaryswitch for movement in unison therewith and having a series yof contactscorresponding in number fte those yof the rotary switch and similarlycontacted by its contacter, the source of current being connected to thefurther switch contacter, and indi* eating means serially connectedbetween the contacts'of the further rotary switch and source of curnentfor visual display of the particular one `of the further rotary switchcontacts made by its contacter which is indicative of the particular oneof the contacts of the rotary switch made by its contacter.

References Cited in the iile of this patent UNITED STATES PATENTS1,637,606 Deurent Aug. 2, 1927 2,085,442 Newell June 29, 1937 '2,192,251Y Whittaker Mar. 5, 1940 2,305,326 :Swallow Dec. 15, 1942 2,346,238Schmidt et al. Apr. 11, 1944 2,350,454 Goebel Iune`6, 1944 2,398,178Ellison lApr. 9, 1946 f 2,630,181 Solum Mar. 3, 1953 2,665,589 RusherIan. 12, 1954 2,848,677 Stockwell Aug. 19, 1958 2,880,652 Welte Apr. 7,1959 2,901,615 Deven Dorf Aug. 25, 1959 2,905,029 Gustafson Sept. 22,1959 2,926,535 Heselwood' Mar. 1, 1960

1. AN INDEXING APPARATUS COMPRISING AN INDEXING GEAR, A PAWL MECHANISMMOVABLE BETWEEN TWO POSITIONS ENGAGING THE INDEXING GEAR IN ONEDIRECTION OF MOVEMENT ONLY TO ROTATE THE GEAR INCREMENTALLY, A FLUIDMOTOR INCLUDING A RECIPROCATING PISTON AND A ROD, THE ROD EXTENDINGBEYOND THE MOTOR AND CONNECTED TO THE PAWL MECHANISM FOR IMPARTINGRECTILINEAR MOTION THERETO, A FLUID SLIDE VALVE HAVING A RECIPROCATINGSLIDE ELEMENT THEREIN, ARMATURES CONNECTED TO THE SLIDE ELEMENT FORMOVEMENT THEREWITH AND EXTENDING BEYOND THE VALVE AT OPPOSITE ENDS OFTHE SLIDE ELEMENT, CONDUITS FLOW-CONNECTING THE FLUID SLIDE VALVE WITHTHE MOTOR FOR INTRODUCING FLUID FROM THE VALVE TO OPERATE THE MOTORPISTON SELECTIVELY FROM ONE POSITION TO ANOTHER WHEREBY THE MOTOR PISTONROD IS RECIPROCATED, SOLENOID COILS CONNECTED IN PARALLEL AND COUPLEDMAGNETICALLY TO EACH OF THE ARMATURES, A SOURCE OF CURRENT CONNECTED TOEACH OF THE SOLENOID COILS, A SWITCH CONNECTED IN SERIES WITH EACH OFTHE SOLENOID COILS AND THE SOURCE OF CURRENT, BOTH SWITCHES BEINGNORMALLY OPEN AND POSITIONED FOR TRIPPING ALTERNATELY BY TRAVEL OF THEPAWL MECHANISM SUCH THAT THE COILS ARE ENERGIZED ALTERNATELY TO MOVE THESLIDE ELEMENT OF THE VALVE FOR CONTROLLED MOVEMENT OF THE MOTOR PISTONBY FLUID PORTED FROM THE VALVE SELECTIVELY ON BOTH SIDES OF THE PISTON,A RELAY WITH A CONTACTOR CONNECTED IN SERIES BETWEEN THE CURRENT SOURCEAND THE SWITCHES AND WITH A COIL FOR OPERATING THE CON-